VMware Backups Fail with Error "Unable to open the disks for virtual machine"

VMware backups can fail when a proxy or MediaAgent uses a self-signed certificate to connect to an ESX host.

Symptoms

VMware backups fail with the following error message:

Unable to open the disks for virtual machine

The vixdisklib.log file contains the following error:

The server refused connection

Causes

This issue can occur for HyperScale nodes that are used as access nodes (VSA proxies) or MediaAgents with self-signed certificates (certificates that are not issued by VMware). In this scenario, the HyperScale nodes act as servers for the VMware VDDK, and the nodes encounter SSL errors when trying to connect to the ESX host.

Resolution

Perform the following steps on the HyperScale nodes that are acting as access nodes or MediaAgents:

1. Back up the /etc/pki and /usr/share/pki directories.
2. Place the certificate file in the /etc/pki/ca-trust/source/anchors folder.
3. Run the update-ca-trust utility to update the certificate authority repository on the node:

update-ca-trust force-enable
update-ca-trust extract